A federal judge in Brooklyn, in an extraordinary opinion (pdf) issued on Wednesday that calls for courts to pay closer attention to how felony convictions affect people’s lives, sentenced a woman in a drug case to probation rather than prison, saying the collateral consequences she would face as a felon were punishment enough.

The judge, Frederic Block of Federal District Court, said such consequences served “no useful function other than to further punish criminal defendants after they have completed their court-imposed sentences.”

The judge noted that there were nearly 50,000 federal and state statutes and regulations that imposed penalties on felons.

Those penalties — denial of government benefits, ineligibility for public housing, suspension of student loans, revocation or suspension of driver’s licenses — can have devastating effects, he wrote, adding that they may be “particularly disruptive to an ex-convict’s efforts at rehabilitation and reintegration into society.”

The issue of collateral consequences has been considered by other courts, but Judge Block’s 42-page opinion, with his call for reform, appears to be one of the most detailed examinations yet.

Judge Block’s sentencing opinion was issued in the case of Chevelle Nesbeth, who was arrested last year at Kennedy International Airport after a search of her luggage turned up 600 grams of cocaine, court records show.

In the opinion, the judge said he considered her crimes to be serious and called her criminal conduct “inexcusable.” But he also listed an array of consequences that she would quite likely face as a result of her felony drug convictions, like being ineligible for grants, loans and work assistance for two years, the duration of her college career.

He noted that the inability to obtain housing and employment stemming from a conviction often results in “further disastrous consequences, such as losing child custody or going homeless,” and leads to many ex-convicts’ “becoming recidivists and restarting the criminal cycle.”

The judge’s ruling does not create a binding legal precedent for other courts, but it is likely to contribute to the national debate about the criminal justice system.

“This is by some distance the most careful and thorough judicial examination” of collateral consequences in sentencing, said Professor Chin, who has written on the subject and whose work the judge cited in the opinion.

“It’s going to generate debate on a critical issue in the criminal justice system — the ability of people convicted of crimes to get on with their lives,” he said.

Ms. Nesbeth had claimed that she was given the suitcases by friends and was unaware they contained drugs. A jury was unpersuaded, convicting her of importation of cocaine and possession of cocaine with intent to distribute, the judge wrote. She faced a sentence of 33 to 41 months under the advisory guidelines.

But in a hearing on Tuesday, Judge Block sentenced Ms. Nesbeth to one year of probation, to include six months of home confinement and 100 hours of community service, and said he would elaborate on his reasoning in the full opinion.

Amanda L. David, a federal public defender representing Ms. Nesbeth, said of the ruling, “It’s refreshing, really, to see a judge considering the ramifications that a lot of people don’t even know about, much less consider, when they think about a person being sentenced.” But even with the probationary sentence, Ms. David said, it was disheartening that there “are all these doors that are closed to her based on her conviction.”

The United States attorney’s office in Brooklyn declined to comment. But in a memo to the judge before sentencing, the office said the collateral consequences of Ms. Nesbeth’s convictions were necessary given her “serious criminal conduct.” Such restrictions, the office added, were “meant to promote public safety, by limiting an individual’s access to certain jobs or sensitive areas,” and “to ensure that government resources are being spent on those who obey the law.”

In the opinion, Judge Block quoted from the work of the legal scholar Michelle Alexander, author of “The New Jim Crow: Mass Incarceration in the Age of Colorblindness.”

“Today a criminal freed from prison has scarcely more rights, and arguably less respect, than a freed slave or a black person living ‘free’ in Mississippi at the height of Jim Crow,” she wrote in one section quoted by Judge Block.

The judge noted that Ms. Nesbeth, who was 20 at the time of her conviction and lived with her mother in New Haven, had been enrolled in college and was also working as a nail technician to help support herself.

Daniel C. Richman, a former federal prosecutor who teaches criminal law at Columbia, added that “however laudable it is for the judge to highlight this problem, his decision can’t solve it, even for this defendant.”

“As the judge himself has made clear,” Professor Richman added, “the source of the problem is outside of his control, all these different statutes.”

Indeed, Judge Block, who has served for more than two decades on the federal bench, said that while judges should consider such consequences at sentencing, it was for Congress and state legislatures “to determine whether the plethora of post-sentence punishments imposed upon felons is truly warranted, and to take a hard look at whether they do the country more harm than good.”